The present invention relates to improved electrodes, particularly adapted for use as anodes in electrochemical processes involving the electrolysis of brines. A variety of materials have been tested and used as anode materials in electrolytic cells. In the past, the material most commonly used for this purpose has been graphite. However, the chlorine overvoltage of graphite is relatively high in comparison, for example, with the noble metals. In addition, in the corrosive media of an electrochemical cell graphite wears readily, resulting in substantial loss of graphite and the ultimate expense of replacement as well as continued maintenance problems resulting from the need for frequent adjustment of spacing between the anode and the cathode as the graphite wears away. As a result, in recent years considerable effort has been expended in attempts to develop improved anode materials and structures. In particular, anodes have been developed which comprise a platinum group metal or oxide thereof, coated on the surface of a valve metal substrate such as titanium. The chlorine overvoltage and dimensional stability of the platinum metals, in corrosive media, represents a substantial improvement over graphite. However, the high cost of platinum group metals or oxides, even when used as a coating, presents an economic disadvantage.
Accordingly, it is an object of the present invention to provide improved electrodes for use as anodes in electrochemical processes involving the electrolysis of brines. It is a further object to provide such anodes which exhibit the desirably low chlorine overvoltage and dimensional stability commonly associated with the noble metals and noble metal oxides while minimizing the amount of noble metal that must be employed.